(a) Field of the Invention
The present invention relates to an apparatus for removing liquid from a suspension. More particularly, the present invention relates to a filtration apparatus using vacuum pressure, compressed air and radiant heat to facilitate extraction of water from a suspension and an air flow within the vacuum chamber to remove the evaporate as a cost-efficient and resource-efficient means of filtering and drying solids in large volumes of suspension to remove interstitial and chemically bound liquids, resulting in up to 100% total solids.
(b) Background of the Invention
Mixtures of liquids and solids, known as suspensions, present expensive disposal problems to the industries that generate them. Unprocessed suspensions typically cannot be disposed of in landfills due to regulations on water content. Even with more permissive regulations, it is much more expensive to transport and dispose of unprocessed suspensions than just solid components because transportation charges and landfill charges correspond to weight.
Additionally, the scope of potential uses of such suspensions is often substantially increased by removal of the liquid component from the solid component. Typically, the value of the dry solids arises from the decrease in weight occasioned by the removal of the liquid fraction, which leads to decreased disposal and transportation costs. Additionally, the recovered dried solids may be commercially valuable, such as if they are useable in other industrial and municipal applications (e.g., renewable fuel) or can be sold in secondary markets, such as in the case where the suspensions comprise paper, fiber, coal or mineral slurries.
Unfortunately, efforts to work around the suspension disposal problems often employ methods lacking environmental soundness. For example, many industries dump suspensions, such as waste products, into holding ponds, which are typically large concrete or plastic lined, man-made pools requiring acres of real estate. The suspensions then sit in these holding ponds while the solid materials settle at the bottom over time with the aid of only gravity. Aside from being a slow process, the potential for the pool lining to fail or result in contamination of the surrounding environment makes this a less-than-desirable solution in terms of both efficiency and environmental impact.
Industrial suspension ponds suffer from significant practical difficulties. To begin, holding ponds have a poor resulting yield (dry solid percentage content). Being passive, it also takes a long time to separate water from solids for a given volume of suspension, as compared to devices that rely on active separation. Keeping up with the output for any given suspension flow rate requires a greater area than if active separation systems are used. Two active separation systems, centrifuge processors and belt presses, each produce higher solid content yields than suspension ponds, however, they lack the ability to utilize thermodynamics to achieve 60-100% dry solid percentage yields. These active separation systems are expensive to purchase and operate and are not readily scaled up or down to handle corresponding volumes of industrial suspension flow rates. The lack of portability and limitations on the amount of material which can be processed in a given time are also a significant limiting factor.
Accordingly, a need is identified for fast and efficient methods and devices for actively separating water from a suspension, and also to produce a resulting solid that is sufficiently dry for use in other applications.